/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2008, by Object Refinery Limited and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * -------------------------
 * KeyedValueComparator.java
 * -------------------------
 * (C) Copyright 2003-2008, by Object Refinery Limited.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * Changes:
 * --------
 * 05-Mar-2003 : Version 1 (DG);
 * 27-Aug-2003 : Moved SortOrder from org.jfree.data --> org.jfree.util (DG);
 * 12-Jan-2005 : Added accessor methods (DG);
 *
 */

package net.droidsolutions.droidcharts.core.data;

import java.util.Comparator;

import net.droidsolutions.droidcharts.common.SortOrder;

/**
 * A utility class that can compare and order two {@link KeyedValue} instances
 * and sort them into ascending or descending order by key or by value.
 */
public class KeyedValueComparator implements Comparator {

	/** The comparator type. */
	private KeyedValueComparatorType type;

	/** The sort order. */
	private SortOrder order;

	/**
	 * Creates a new comparator.
	 * 
	 * @param type
	 *            the type (<code>BY_KEY</code> or <code>BY_VALUE</code>,
	 *            <code>null</code> not permitted).
	 * @param order
	 *            the order (<code>null</code> not permitted).
	 */
	public KeyedValueComparator(KeyedValueComparatorType type, SortOrder order) {
		if (order == null) {
			throw new IllegalArgumentException("Null 'order' argument.");
		}
		this.type = type;
		this.order = order;
	}

	/**
	 * Returns the type.
	 * 
	 * @return The type (never <code>null</code>).
	 */
	public KeyedValueComparatorType getType() {
		return this.type;
	}

	/**
	 * Returns the sort order.
	 * 
	 * @return The sort order (never <code>null</code>).
	 */
	public SortOrder getOrder() {
		return this.order;
	}

	/**
	 * Compares two {@link KeyedValue} instances and returns an <code>int</code>
	 * that indicates the relative order of the two objects.
	 * 
	 * @param o1
	 *            object 1.
	 * @param o2
	 *            object 2.
	 * 
	 * @return An int indicating the relative order of the objects.
	 */
	public int compare(Object o1, Object o2) {

		if (o2 == null) {
			return -1;
		}
		if (o1 == null) {
			return 1;
		}

		int result;

		KeyedValue kv1 = (KeyedValue) o1;
		KeyedValue kv2 = (KeyedValue) o2;

		if (this.type == KeyedValueComparatorType.BY_KEY) {
			if (this.order.equals(SortOrder.ASCENDING)) {
				result = kv1.getKey().compareTo(kv2.getKey());
			} else if (this.order.equals(SortOrder.DESCENDING)) {
				result = kv2.getKey().compareTo(kv1.getKey());
			} else {
				throw new IllegalArgumentException("Unrecognised sort order.");
			}
		} else if (this.type == KeyedValueComparatorType.BY_VALUE) {
			Number n1 = kv1.getValue();
			Number n2 = kv2.getValue();
			if (n2 == null) {
				return -1;
			}
			if (n1 == null) {
				return 1;
			}
			double d1 = n1.doubleValue();
			double d2 = n2.doubleValue();
			if (this.order.equals(SortOrder.ASCENDING)) {
				if (d1 > d2) {
					result = 1;
				} else if (d1 < d2) {
					result = -1;
				} else {
					result = 0;
				}
			} else if (this.order.equals(SortOrder.DESCENDING)) {
				if (d1 > d2) {
					result = -1;
				} else if (d1 < d2) {
					result = 1;
				} else {
					result = 0;
				}
			} else {
				throw new IllegalArgumentException("Unrecognised sort order.");
			}
		} else {
			throw new IllegalArgumentException("Unrecognised type.");
		}

		return result;
	}

}
